Lawn aeration is a topic of discussion on the organic site I referenced earlier in the week. Their expert lawn guy swears by the floculating effects of using a sprayer (backpack is fine, but even just a 2-gallon with a hose and wand is sufficient) with water and a bit of shampoo mixed in. And surprisingly little shampoo. I just looked up the moderator's advice in the forum:

I'm going to suggest you do not go to the trouble of aerating. Instead, use shampoo to soften your soil. Healthy soil is like a sponge. When it is dry it is very hard. When the first drop of moisture hits, it does not soak right in. It takes a few seconds before it soaks in. Once it soaks in, the soil becomes very soft. Shampoo can help create this process.

Use cheap, generic, shampoo. Apply from a hose end sprayer at a rate of 3 ounces per 1,000 square feet. Apply right before you irrigate (1 inch). Next month spray it again. That should be all you need for the rest of the season. Then sit back and wonder at the amazing soil as it softens during rain and after irrigation and hardens up again a few days later. But when watering, do not go by the soil. Go by the grass. Grass can grow very nicely in hard soil.

Scroll down on that forum page and he gives a scientific explanation of how that works, last post on the page.

I have so many yard chores to do right now it's difficult to predict which one will strike my fancy when I walk out the door in a few minutes. I'll report back later.